The police argue that if an accused person elects to stand trial, he has about a 50/50 chance of being convicted. Critics of what are clearly seen as excessively high rates of acquittal are seeking reasons. If it is true that many prosecutions fail because of deficiencies in the Crown case, then it may well be that the police and the Crown law authorities need to be more careful in their work. Additionally, juries may acquit even though they are satisfied that all the legal requirements for a conviction exist. The central questions raised by this debate remain, including an appropriate acquittal rate, criteria for determining the appropriate rate, and degree of variation from the appropriate figure that would be expected or acceptable. It is suggested, however, that ultimately these are questions of values and principles which cannot be resolved through empirical investigation alone. Five tables and 31 references are provided.